Salad dressing

ABSTRACT

The present invention relates to stable pourable emulsions of the type vinaigrette. Stability is attained by incorporating into the continuous oil phase a small amount of solid fat, such as hardened rapeseed oil. The product resembles to a large extent traditional home-made vinaigrette.

The present invention refers to a pourable water-in-oil emulsion whichis known as "vinaigrette" and which is a very familiar and appreciatedsalad dressing. Traditionally such salad dressing is made by mixingabout 75 wt. % of oil and about 25 wt. % of vinegar until an emulsionresults. The emulsion optionally is flavoured with usual dressingingredients. Because of quick phase separation such dressing is madeimmediately before use.

A known industrially prepared imitation vinaigrette comprises a watercontinuous emulsion containing 25-50 wt. % dispersed oil and astabiliser, such as a gum, a modified starch or a suitable protein.However, the product does not resemble the home-made vinaigrette in itsappearance, taste and wetting behaviour. It has a milky appearance andis experienced as synthetic. As a result of the poor wetting behaviourthe dressing does not properly adhere as a thin film on the leaves ofthe salad, but drips to the bottom of the salad bowl.

Efforts to stabilise home-made vinaigrette by incorporating anemulsifier into the emulsion have failed, because the desired pourabletheology was lost and a mayonnaise-like product was obtained.

It is therefore an object of the present invention to provide avinaigrette type pourable emulsion having a good taste, appearance andconsistency. It is a further object of the invention to provide an oilphase suitable for the preparation of such emulsion. Another object ofthe invention is to provide a process for the preparation of the abovepourable emulsion.

According to the present invention it has become possible to prepare anoil phase suitable for use in the preparation of a stable pourableemulsion with a dispersed acid water phase. By a stable emulsion ismeant a dispersion which after its preparation can be kept at atemperature of 2°-20° C. under quiescent conditions for at least one daywithout any substantial phase separation being observed. Preferablyemulsion stability is maintained for at least six months and still morepreferably for at least nine months. Phase separation is here defined tobe substantial when on a sample of the present vinaigrette a separatedlayer is clearly visible of which the thickness is at least 2% of theheight of the remainder of the sample.

In order to be appreciated as a salad dressing the water phase should beacid, having a pH which preferably is 3.5 or less.

The emulsion according to the invention is preferably characterised bycontaining an oil phase which is structured by solid fat.

The invention is preferably applied to water-in-oil emulsions containing50-90 wt. % fat on total emulsion. The fat phase is a liquid oil inwhich solid fat is incorporated, preferably in such amount that thesolids fat content at 20° C. (N₂₀) is 0.1-10, preferably 0.1-3.0, morepreferably 1 and at 40° C. (N₄₀) of 0.1-3.0, preferably 0.5-2.0, morepreferably 0.9, as established by a NMR measurement.

If not indicated otherwise, all wt. % throughout this specification andappending claims are calculated on the emulsion weight.

The amount of solid fat should be low enough to ensure that the eventualdressing has a pourable consistency.

The amount of solid fat (N₂₀ value) is established by the NMR-method asdescribed in Fette, Seifen, Anstrichmittel 80, (1978), 180-186.

Solid fats suitable for incorporating into the vinaigrette oil are e.g.hardened rapeseed oil, hardened sunflower seed oil, hardened soy beanoil such as BO69, hardened palm oil such as PO58, and mixtures of them.Most preferred is fully hardened rapeseed oil (RP70). Suitable liquidoils are vegetable oils such as sunflower seed oil, rapeseed oil,soybean oil, olive oil and mixtures of them.

In this specification, unless otherwise indicated, the term `fat` andthe term `oil`, when used in a general sense, refer to edible fattysubstances including natural or synthesized fats and oils consistingessentially of triglycerides such as, for example, soybean oil,sunflower oil, palm oil, coconut oil, and to non-toxic fatty materialshaving properties similar to triglycerides, which materials may beindigestible, such as for example polyol fatty acid polyesters. Theterms fat and oil are used interchangeably, with the proviso that oildenotes a fat which is liquid at ambient temperatures.

In this specification the term `polyol fatty acid polyester` is intendedto refer to any polyester or mixtures thereof, of which on an averagemore than 70% of the polyol hydroxyl groups have been esterified withfatty acids. In this regard by `indigestible` is meant that at leastabout 70% by weight of the material concerned is not digested by thehuman body.

The invention comprises also a method for the preparation of a stable,pourable emulsion having a continuous fat phase which comprises thesteps

A. dissolving a solid fat into a liquid vegetable oil at a temperaturewhere all solid fat has melted, whereby the amount of solid fat ischosen such that the eventual oil is as defined hereinbefore,

B. cooling under high shear conditions within 5-120 seconds, preferably5-30 seconds, to a temperature of -5° C. to -15° C., preferably to about-10° C.,

C. warming up under low shear conditions during at least two minutes toa temperature of -5° C. to +5° C., preferably about 0° C.,

D. mixing at 10°-40° C. under low shear conditions 50-90 weight parts ofthe prepared fat phase with 10-50 weight parts of an acid water phasewhich has a pH of 3.5 or less until the water phase is fully dispersedinto the oil phase and an emulsion is obtained with a stability of atleast one day.

A suitable apparatus for rapid cooling under high shear conditions is aVotator™ A-unit, which operates at a rotor speed of 1300-1700 rpm,preferably of 1500 rpm. A suitable temperature of the cooling liquid is-20° C. A suitable apparatus for the warming up step is a Votator™C-unit, which operates at a rotor speed of 30-100 rpm, preferably 50rpm.

For obtaining a vinaigrette type pourable emulsion the obtained oilphase obtained according to step C. is emulsified according to step D.with an acid water phase. Or, alternatively, step D. is postponed andthe emulsion is prepared shortly before kitchen or table use. The latteroption has the special advantage, that the oil phase can be combinedwith any desired acid water phase, preferably by choosing the vinegartype most preferred by the user of the product.

Therefore, a particular embodiment of the invention is the use of oilwith a solids fat content at 20° C. (N₂₀) of 0.1-10, preferably0.1-3.0.for preparing a stable dressing containing a continuous ediblefat phase and a dispersed acid water phase.

The emulsion is prepared by stirring the ready water phase at 10°-40°C., preferably at ambient temperature, into the fat phase under lowshear conditions, preferably with a high convection effect. Suitably alow shear, low speed blender of a type which is usually applied fordressing manufacture is used for that purpose. Stirring is continueduntil the water phase is totally dispersed into the oil and a yellowoily product is obtained. The water droplets advantageously have anaverage size of 5-30 μm, preferably 15 μm. Stirring for a too long timeor with too much shear yields an undesirably pale coloured dressing onaccount of the particles becoming too small. To prevent destroying thestructure of fat crystals care should be taken that the temperature doesnot rise over 40° C.

Applicant not wishing to be bound by theory believes that the highmelting fat forms in the oil a fragile agglomerate of fine crystals inwhich the aqueous droplets are captured, so that phase separation isprevented.

For the preparation of an acid water phase an edible acid should beused. Preferably vinegar is used, preferably in an amount of 10-25 wt.%, more preferably 12.5 wt. %. Optionally, 10-90 wt. % of the vinegar issubstituted by one or more other edible acids, provided the pH of theeventual water phase is not higher than 3.5. If not indicated otherwise,all wt. % through this specification and appending claims are calculatedon the emulsion weight. Optionally, other flavouring ingredients such assalt, pepper, mustard, herbs and spices are incorporated into theemulsion. The total amount of other flavouring ingredients preferably is0.01-4 wt. %.

When the water phase is not immediately mixed with the ready oil phaseit is convenient to add at least a part of the optional ingredients tothe oil phase. Preferably, the optional ingredients are admixed with theacid water phase which is then emulsified with the oil phase yieldingthe pourable emulsion of the invention.

Typically the emulsion does not need an emulsifier to obtain itsstability. But, according to another embodiment of the invention someemulsifier, preferably 0.2-1.0 wt. %, more preferably about 0.5 wt. %,may be added to enhance the emulsion stability, particularly when thewater content is over 20%. In that case it is used as a supplement tothe stabilisation which is primarily based on the solid fat crystals andno undesired rheology effect has been observed.

An emulsifier is preferably added to the fat phase, Suitable emulsifiersare e.g. monoglycerides, diglycerides, phospholipids and polyglycerolesters.

If desired the water phase may be stabilised by incorporating any waterphase stabiliser. Suitable stabilisers are e.g. gelatin, gums, alginate,pectin, modified starches and proteins.

The dressing of the invention has a good pourability and fluidity. Themouthfeel is pleasant: fatty and full. With respect to taste, appearanceand wetting behaviour it resembles traditionally home-made vinaigrette.Stability is ensured for at least six and preferaby nine months.

EXAMPLE 1

The oil and water phase are prepared separately. After both phases havebeen prepared the final product may be prepared either immediately or atwish shortly before use.

The oil phase is prepared by dissolving 1 wt. % fully hardened rapeseedoil, melting at 70° C. (RP70) in sunflower oil at 80° C. in a stirredvessel. After all RP70 has been dissolved in the oil, resulting in aclear oil the oil phase is intermittently cooled to 55° C. and then ispumped through 2 Votator™ A-units in series followed by acrystallisation unit (C-unit). In the first A-unit the oil is cooledfrom 55° C. to -8° C. at high rotor speed (1400 RPM). The residence timeof the oil in the A-units is 20 to 30 seconds. In the second A-unit theoil phase is kept at low temperature (-5° C.) at high rotor speed (1400RPM). The rapid and deep cooling at high rotor speed are stronglypreferred to obtain an oil phase in which the RP70 crystals are veryfinely dispersed. Two A-units in series will result in more finelydispersed RP70 crystals than one single A-unit. When dispersing the RP70crystals is carried out under these conditions a stable emulsion willresult. After the second A-unit the oil phase enters the C-unit. Theresidence time in the C-unit is 2 to 3 minutes and the temperature ofthe oil during this period is kept at 0° C. The oil phase is stirred atvery low rotor speed (50 rpm) allowing the RP70 crystals to fullycrystallise in the oil. After the C-unit the oil has a temperature of 5°C. and is stored until use. Storage temperature is ambient temperature,but should not exceed 40° C.

The water phase is prepared at ambient temperature. 50 wt. % 10°vinegar, 4 wt. % mustard, 4 wt. % salt and 0.4 wt. % white pepper areadded to 41.6% wt. % (tap) water. Optionally herbs, flavours and spicescan be added. The water phase is mixed thoroughly and stored at roomtemperature.

The final product is prepared by slowly adding 25 wt. % water phase to75 wt. % oil phase under stirring at ambient temperature. Mixing ispreferably carried out with a ribbon stirrer or another low shearstirrer. Mixing is continued for 5 minutes after the water phase hasbeen dispersed completely in the oil phase. The final emulsion is storedcool, preferably at 5° C., anyway storage temperature should not exceed40° C.

After six months the emulsion did not show any phase separation.

EXAMPLE 2

The oil phases according to compositions 1-6 were prepared:

    ______________________________________                                                                wt %                                                  composition                                                                              oil          spe1   spe2                                           ______________________________________                                        1           0           93     7                                              2          20           74     6                                              3          40           55     5                                              4          50           46     4                                              5          60           37     3                                              ______________________________________                                    

Both spe1 and spe2 are sucrose polyesters.

The oil is sunflower oil. The fatty acids of spe1 have the followingcomposition:

    ______________________________________                                                       spe1                                                           Fatty acid     weight %                                                       ______________________________________                                        Lauric acid    0.2                                                            Myristic acid  0.2                                                            Palmitic acid  11.8                                                           Stearic acid   8.6                                                            Arachidic acid 0.3                                                            Oleic acid     53.8                                                           Elaidic acid   --                                                             Linoleic acid  22.9                                                           Linolenic acid 1.0                                                            Others         1.2                                                            Total          100                                                            ______________________________________                                    

The octaester content of this material is 78.1 wt. %, the OH value 6.1and the clearpoint as measured with DSC of about 20° C.

The fatty acids of spe2 have the following composition:

    ______________________________________                                                       spe2                                                           Fatty acid     weight %                                                       ______________________________________                                        Caprylic acid  --                                                             Lauric acid    0.3                                                            Myristic acid  1.4                                                            Palmitic acid  48.9                                                           Stearic acid   48.9                                                           Arachidic acid 0.4                                                            Elaidic acid   0.1                                                            ______________________________________                                    

Spe2 has a OH-value of 4.1 and a clearpoint (DSC) of 55° C.

The processing was as follows: Spe1 and the oil were mixed, Spe2 isdissolved in the mixture at 80° C. in a stirred vessel. The rest of theprocessing was as in example 1. The six oil phases may be used as suche.g. as a pourable oil, or, according to example 1, may be mixed with awater phase to prepare the six corresponding vinaigrette compositions.Suitable results may be obtained by mixing the above oil phase with thewater phase of example 1 in a weight ratio of 3:1.

After six months none of the emulsions did show any phase separation.

We claim:
 1. A vinaigrette salad dressing which is a stable pourablewater-in-oil emulsion comprising a continuous edible fat phase and adispersed acid water phase, wherein the acid water phase has a pH whichis not higher than 3.5.
 2. Dressing according to claim 1, wherein thefat phase comprises 50-90 wt. % edible fat on total emulsion. 3.Dressing according to claim 1, wherein the edible fat phase is a liquidoil with a solids fat content at 20° C. (N₂₀) of 0.1-10 and at 40° C.(N₄₀) of 0.1-3, as established by a NMR measurement.
 4. Dressingaccording to claim 1, wherein the edible fat phase contains fullyhardened rapeseed oil.
 5. Dressing according to claim 1, wherein theacid water phase comprises vinegar in an amount of 10-25 wt. % on totalemulsion.
 6. Dressing according to claim 1, wherein the emulsioncomprises 0.01-4 wt. % of one or more ingredients selected from thegroup consisting of mustard, pepper, salt, herbs and spices.
 7. Dressingaccording to claim 1, wherein the emulsion is stable for at least sixmonths, preferably for at least nine months.
 8. Method for thepreparation of a stable, pourable emulsion having a continuous fat phaseand a dispersed acid water phase comprising the stepsa. dissolving asolid fat into a liquid vegetable oil at a temperature where all solidfat has melted, whereby the amount of solid fat is such that theresulting oil is a liquid oil with a solids fat content at 20° C. (N₂₀)of 0.1-10 and at 40° C. (N₄₀) of 0.1-3, as established by a NMRmeasurement, b. cooling under high shear conditions within 5-120 secondsto a temperature of -5° C. to -15° C., c. warming up under low shearconditions during at least two minutes to a temperature of -5° C. to +5°C., d. mixing at 10°-40° C. under low shear conditions 50-90 weightparts of the thus prepared fat phase with 10-50 weight parts of an acidwater phase which has a pH of 3.5 or less until the acid water phase isfully dispersed into the fat phase and an emulsion comprising acontinuous edible fat phase and a dispersed acid water phase isobtained.
 9. An edible fat composition comprising a liquid oil with asolids fat content at 20° C. (N₂₀) of 0.1-10 and at 40° C. (N₄₀) of0.1-3, as established by a NMR measurement, said fat composition alsocontaining 0.01-4 wt. % of one or more dressing ingredients selectedfrom the group consisting of mustard, pepper, salt, herbs and spices.10. A stable vinaigrette emulsion according to claim 1, said emulsioncomprising from 50-90 wt. % of the fat phase and 50-10 wt. % acid waterphase.